Water has a significant influence on the flavour and body of beer, though not as great as the contribution made by malted barley and other grains; by hops; and by the brewer himself.
If barley took up more water from the soil, it would contain juice, as grapes do. That would make it – like the grape – easy to use in the production of drinks. It would also render it – again like the grape – soft, fragile, and more susceptible to damage and deterioration. Being drier and thicker-skinned makes barley tougher and more resilient. Barley flourishes in a wider range of soils and climates, and especially in cooler places than the grape. That is why the Central Northwestern countries of Europe typically produce beer, while the warmer Southeast favours wine. Barley is tough in more senses than one. Not only can it stand up to the weather, it is also tough to chew; too hard to eat, for example, in its raw state. It can be softened by being turned into malt.
This means that it is steeped in water until it begins to sprout, then dried. After being malted, the grain is biscuity, and soluble. In the brewhouse, the malt is mixed with water.
This is the principal use of water as an ingredient in beer. And this is where the character of the water most influences the flavour of the brew.
In the simplest method, the mixture of malted grain and water sits in a vessel like a gigantic coffee filter. The liquid that filters through is the “juice” of the barley or other grains (eg. wheat, oats, rye).
Extra water is run through (like the second or third pull on an espresso machine), and all the “juices” ollected are boiled in a large kettle with the aromatic cones of the hop plant. When the brew has cooled, it is moved to a fermentation vessel. Yeast is added, fermentation starts, and beer will shortly be served. When the “coffee filter” is cleaned, it contains lots of husky grain residue.
This “spent grain” cannot be “squeezed” totally dry, so a substantial amount of water is wasted here. (Spent grain is usually given to local farmers as cattle feed). When the kettle is boiled, more water is lost in evaporation.
A great deal of water is also used in washing equipment, bottles, casks and the brewhouse itself. When every village had a brewery, the total volume of water needed was manageable. These breweries each served just one pub, or perhaps two or three. They were like mom-and-pop bakeries. When steam power made it possible to brew on an industrial scale, and the birth of railways made it possible to distribute beer throughout a big city or region, and eventually nationwide, far greater volumes of water were needed.
When a regional brewery was planned, a site was chosen where there was plenty of water from springs or wells. A brewery on an industrial scale could not afford to lose its supply for even the odd day in a dry summer. The water must be inexhaustible, consistent, clean and pure.